You have seen that five of these twenty words have <rr> because of simple addition and five of them have <rr> because of twinning. Find these ten in the list above and cross them off.

2. When the prefixes ad-, com-, and in- are added to stems that start with an <r>, they assimilate to ar , cor-, and ir- .

3. Ten of the twenty words above with [r] spelled <rr> start with an assimilated form of ad-, com-, or in-. Find them, write them in the left column below, and analyze them to show the assimilation that leads to the <rr>:

Word

Analysis: Prefix + Stem

irrigation

in+ r + rigation

arrest

ad+ r + rest

arrival

ad+ r + rival

correctly

com+ r + rectly

corruption

com+ r + ruption

irritate

in+ r + ritate

arrange

ad+ r + range

irregular

in+ r + regular

correspond

com+ r + respond

irresponsible

in+ r + responsible

4. The following words each contain two prefixes and a stem. See if you can analyze them to show where the <rr> comes from: